Guide bed for sewing machines



Jan. 1, 1963 L. H. ERBLAND GUIDE BED FOR SEWING MACHINES Filed Jan. 50,1961 INVEN TOR. LOREEN H. ERBLAND ROBERT J. PATCH ATTORNEY FIG. 5

United States Patent Ofitice 3,871,091 Patented Jan. 1, 1963 3,071,891GUIDE BED FQR SEWING MACHWES Loreen H. Erbland, 1525 N. Van Ness St,Santa Ana, (Ialif. Filed Jan. 38, 1961, Ser. No. 85,562 3 Claims. (Cl.112-268) The present invention relates to guide beds for sewingmachines, and more particularly to sewing machine beds provided witharrangements for guiding material relative to the bed and relative toother portions of the material as the material moves across the bed andthrough the sewing mechanism.

It is an object of the present invention to provide sewing machinemechanism which will give a visual indication of the accuracy of theformation of the seam, both relative to the bed and relative to otherportions of the material.

Another object of the present invention is the provision of sewingmachine mechanism which will permit quick and accurate formation ofsewed seams.

Finally, it is an object of the present invention to provide sewingmachine structure which will be quick and easy to manufacture, which canbe inexpensively incorporated in new sewing machines or by conversion inold sewing machines, and which will be easy to operate, dependable,rugged and durable in use.

Other objects and advantages will become apparent from a considerationof the following description, taken in connection with the accompanyingdrawing, in which:

FIGURE 1 is a fragmentary plan view of the region of a sewing machinethroat plate according to the present invention;

FIGURE 2 is a section on the line 22 of FIGURE 1 and showing the novelthroat plate of the present invention in cooperation with the sewingmechanism of the machine; and

IGURE 3 is a View on the line 3-3 of FIGURE 1 and showing a furtherrefinement of the present invention.

Referring now to the drawing in greater detail, there is shown sewingmachine structure comprising a bed I having a horizontal upper workingsurf-ace 3. Bed it is in the form of the usual flat plate and has theusual opening 5 therethrough having a semi-circular end portion andbounded by a narrow shelf 7 on which rests a throat plate 8 of the usualshape. Fastening screws 9 removably secure throat plate 8 to shelf 7 inthe usual way. As is also conventional, the upper surface of throatplate 8 is flat and horizontal and flush withthe rest of working surface3, while fastening screws 9 are flat-headed and flush with workingsurface 3.

In the illustrated embodiment, the sewing mechanism is located at somedistance inward of the outboard end of bed 1, and opening 5 extends allthe way out to the outboard end. Accordingly, a slide cover plate ll ofrectangular configuration is provided to fill opening 5 endwiseoutwardly of the outer straight edge of throat plate 8.

Throat plate 8 is provided with the usual needle aperture 13therethrough, and also with elongated parallel slots 15 of ordinaryconfiguration and arrangement. The usual work feed mechanism 17terminates at its end in feed dogs 19 which have serrated upper surfacesand which are the same in number as slots 15 and extend upwardly throughslots 15. This work feed mechanism is conventional and is disposedbeneath working surface 3.

The usual vertical needle 21 is carried by needle bar 23 and extendsdownward through needle aperture 13, while a conventional presser bar(not shown) carries at its lower end the usual presser foot 25 whichextends on either side of needle 21 and coacts with feed dogs 19properly to position and advance the material.

All of the structure as described thus far is conventional and is nodeparture from the prior art.

The invention departs from the prior art, however, in that throat plate8 is light-penetrable, at least adjacent slots 15 and needle aperture13. Preferably, throat plate 8 is transparent and is made of glass orhard plastic. Fabrication from hard plastic is easier than fabricationfrom glass, and a hard plastic throat plate is less subject to breakagethan a glass throat plate. Moreover, although hard plastic is moresubject to scratching than is glass, such scratching is not detrimentalto the present invention, for although such scratching decreases thetransparency of the material of the throat plate, it does notsubstantially alter the light-penetrability of the material. As will bepointed out later, it is the light-penetrability of the material that isthe important feature of throat plate 8, and a transparent throat plateis preferred simply because a transparent material is the most highlylighttransmissive.

An electric light source 27 is a vital feature of the present inventionin combination with the light-penetrable portion of throat plate 8adjacent slots 15 and needle aperture 13. Light source 27 comprises anelectric light bulb 29 disposed beneath working surface 3 closelyadjacent slots 15 and needle aperture 13. Bulb 29 is replaceably mountedin a socket 31 carried by a bracket 33 including a reflector 35 which isupwardly concave and is so disposed as to reflect light emitted downwardfrom bulb 29 back up toward slots 15 and needle aperture 13. Bracket 33is held in place on the underside of the plate comprising bed 1 by meansof attachment screws 37 passing through the bed plate.

The purpose and function of the essential elements of the invention willnow be apparent. When throat plate 8 with its light-penetrable portionis in position as shown and electric light source 27 is turned on, lightwill shine up through throat plate 8 from below at least adjacent needleaperture 13 and slots 15. Most fabrics are to some extentlight-transmissive, at least sufficiently so that a strong light cantosome degree be seen to shine through them from the side opposite theviewer. Accordingly, it will be appreciated that when such fabric is runbetween feed dogs 19 and presser foot 25 in multiple layers, hiddenedges or hems or seams or lines of stitching will show up in silhouetteand their location can be determined even though they "do not appear onthe uppermost layer of fabric. In this way, the line of stitching thatis being formed can be properly oriented relative to such hidden seamsor lines and can be made parallel thereto at selected distances or canbe made precisely to coincide with desired portions of any hidden layerof fabric.

Another desirable feature of the present invention is not restricted tooperation with multiple layers of fabric. This further feature of theinvention arises from the fact that when thread of the same color as theworkpiece is being applied by a sewing machine, the resulting line ofstitching is often not readily visible by reflected light incident fromabove. But the applied line of stitching is distinctly apparent whenlight shines through the material from below, for the line of stitchingprovides in effect a relatively light-impervious line along the fabricthat shows up as a distinctively darker line across the field of lightfrom below.

In its preferred form, throat plate 8 is not light-trans missive overits entire area, but only adjacent slots 15 and needle aperture 13.Spaced from needle aperture 13 and slots 15, throat plate 8 preferablyhas an opaque portion which in the preferred form of the invention is asilvered portion 39. Broadly, silvered portion 39 c mprises a portion ofthroat plate 8 which is highly reflective on its underside. If throatplate 8 is made of glass, then silvered portion 39 may be applied bysilvering in the usual manner to the upper surface of throat plate 8, orby front silvering on the lower surface of throat plate 8. Applicationof the reflective layer to the undersurface of throat plate 8 has theobvious advantage that it is not nearly so subject to wear as if it ison the upper surface as shown. Of course, the highly reflective surfacemay be applied to throat plate 8 by other means such as vapor depositionof metals such as aluminum, or in any of a variety of other ways. Ifthroat plate 8 is hard plastic, then the highly reflective layer may beapplied to either face by a variety of methods including the applicationof thin foil, etc. Of course, it will be understood that the purpose ofthe highly reflective surface is to reflect light rather than to reflectprecise images, so that the reflective surface need not at all be anoptical surface.

The highly reflective undersurface portion of throat plate 8 performstwo functions: (1) because it is opaque, it permits light source 27 tobe positioned considerably closer to the sewing mechanism withoutshining directly in the operators eyes; that is, it masks light source27 to prevent glare; and (2) because it is highly reflective downward,it increases the intensity of illumination below working surface 3 andincreases the reflected light which finds its way back up through thelight-transmissive portions of throat plate 8. Of course, throat plate 8could be made in the first place to be only the size and shape of itslight-transmissive portions, but this arrangement is less preferred inthat it would require modification of existing sewing machine bedstructure in which the size and shape of opening 5 is fairly standard.

Another feature of the present invention which coo-perates to produce aresult closely related to the result of the structure already describedis shown adjacent the bottom of FIGURE 1 and in FIGURE 3 of the drawing.As is there shown, bed 1 is provided with an elongated recess 41 openingtherethrough that extends laterally from the edge of the bed plate andopens into opening 5. Recess 41 has parallel straight edges, and a shelf43 like shelf 7 runs along each edge of recess 41. A light-transmissive,preferably transparent, alignment plate 45 of glass or hard plasticrests on shelf 43 and completely closes recess 41 and has its uppersurface as a part of and flush with the remainder of working surface 3.Plate 45 thus extends endwise of and for a considerable distance endwisebeyond the lengths of slots 15. Plate 45 may be held to shelf 43 byscrews (not shown) or it may have sliding tongue and groove engagementwith the side edges of recess 41, or as in the illustrated embodiment itmay be made of hard plastic of limited resiliency and simply snap intoplace. 7

Plate 45 is provided with indicia 47 which are elongated in thedirection of the length of slots and are disposed a considerabledistance endwise beyond slots 15. In the illustrated embodiment, theyare parallel to slots 15. They are spaced apart laterally of theextended length of slots 15, that is, they are spaced apart in adirection perpendicular to slots 15 and are disposed on either side ofand are parallel to a prolongation of the length of slots 15.Preferably, indicia 47 are parallel straight lines. They arelight-impenetrable and they are preferably formed on plate 45 by markingas with indelible paint or ink in long recesses on the upper surface ofplate 45, so that they will not readily wear off.

A second electric light source 49 is provided closely adjacent but belowindicia 47 and below working surface 3, comprising a second electriclight bulb 51 in a socket 53 on a bracket 55 having a reflector 57 todirect light emitted downward from bulb 51 back up to indicia 47, andattachment screws 59 to hold bracket 55 to the underside of the platecomprising bed 1.

Plate 45 functions in a manner quite similar but distinguishable fromthe manner in which the light-transmissive portion-s of throat plate 8function. Specifically, indicia 47 now play the part that was played bya hidden edge or seam in connection with throat plate 8. Aslightpenetrable fabric passes across working surface 3, downward as seenin FIGURE 1, from needle aperture 13 over alignment plate 45, the lineof stitching produced by needle 21 shows up first on thelight-transmissive portions of throat plate 8 and then across alignmentplate 45 as a relatively dark line across the light field of theilluminated fabric. At the same time, the light from below plate 45shining up through plate 45 makes indicia 47 show up as dark lines asseen through the fabric that covers plate 45. The dark line of thestitching can then be aligned with any selected portion of indicia 47 soas accurately to orient the fabric and the stitching as desired. Inother words, indicia 47 provide a guide for the formation of the seameven though these indicia are invisible when covered by the fabric asseen in reflected light incident from above, for the light from belowbrings them out even through the fabric. For this reason, it ispreferred that indicia 47 be disposed on the upper surface of plate 45rather than on the undersurface, so that they are as close as possibleto the fabric which covers them and accordingly cast a. sharper shadowon the fabric than if they were spaced from the fabric by the thicknessof plate 45.

From the above discussion of the light-transmissive portions of throatplate 8 and alignment plate 45, it will be obvious that the aim of thesemembers is to make sure that a maximum of light is transmitted upwardthrough the fabric which covers them, over a relatively broad field, sothat the illuminated field will appear as light as possible in contrastto the darker lines of stitching or of indicia 47. Therefore, it will beappreciated that one desirable form of the light-transmissive portionsof throat plate 8 and of alignment plate 45 is that they be frosted ontheir underside so as to make sure that the light that is transmittedupward through them provides a uniformly bright field. Thus, althoughthe material of these members may be transparent, in one desirable formthe material as a whole may be translucent because frosted.

From a consideration of the foregoing description, it will be obviousthat all of the initially recited objects of the present invention havebeen achieved.

Although the present invention has been described and illustrated inconnection with preferred embodiments, it is to be understood thatmodifications and variations other than those specifically describedabove may be resorted to without departing from the spirit and scope ofthe invention, as will be readily understood by those skilled in thisart. Such modifications and variations are considered to be within thepurview and scope of the present invention as defined by the appendedclaims.

What is claimed is:

1. In a sewing machine having a bed having an upper horizontal workingsurface, work feeding mechanism below said surface and including atleast one feed dog, said surface having at least one horizontallyelongated slot opening therethrough through which said at least one feeddog extends; the improvement comprising the bed beinglight-penetrablefor a substantial distance endwise of said at least oneelongated slot, light-impenetrable indicia on a light-penetrable portionof the bed and disposed a substantial distance from and endwise of saidat least one slot, and an electric light source disposed below saidsurface and adjacent said indicia.

2. Apparatus as claimed in claim 1, there being a plurality of saidindicia spaced apart in a direction perpendicular to a prolongation ofthe length of the slot and extending on both sides of said prolongationof the length of the slot.

3. In a sewing machine having a bed plate having an upper horizontalworking surface, the bed plate being provided with an opening adjacentthe sewing mechanism, a throat plate secured in assembly with the bedplate and having an upper surface substantially flush with the upper 5 6surface of the bed plate, work feeding mechanism below metal coating onthe under surface thereof exposed to light said surfaces and includingat least one feed dog, the from and directly above said electric lightsource. throat plate having at least one opening therethrough throughwhich said at least one feed dog extends, the Regelemes Cited in thefile of fills Patent throat plate being light-penetrable over asubstantial area thereof adjacent to said at least one opening, and anUNITED STATES PATENTS electric light source disposed below said surfacesand ad- 2 ireeman g g jacent said at least one opening; the improvementcomprisyres c ing a portion of the throat plate spaced from said atleast REI N PATENT one opening being ofthe light-penetrable material ofthe 10 6,384 Great Britain Man 25, 1905 rest of the throat plate buthaving a highly light reflective

1. IN A SEWING MACHINE HAVING A BED HAVING AN UPPER HORIZONTAL WORKINGSURFACE, WORK FEEDING MECHANISM BELOW SAID SURFACE AND INCLUDING ATLEAST ONE FEED DOG, SAID SURFACE HAVING AT LEAST ONE HORIZONTALLYELONGATED SLOT OPENING THERETHROUGH THROUGH WHICH SAID AT LEAST ONE FEEDDOG EXTENDS; THE IMPROVEMENT COMPRISING THE BED BEING LIGHT-PENETRABLEFOR A SUBSTANTIAL DISTANCE ENDWISE OF SAID AT LEAST ONE ELONGATED SLOT,LIGHT-IMPENETRABLE INDICIA ON A LIGHT-PENETRABLE PORTION OF THE BED ANDDISPOSED A SUBSTANTIAL DISTANCE FROM AND ENDWISE OF SAID AT LEAST ONESLOT, AND AN ELECTRIC LIGHT SOURCE DISPOSED BELOW SAID SURFACE ANDADJACENT SAID INDICIA.